Making bonded felt



April 1 M. T. HOFFMAN 2,881,505-

MAKING BONDED FELT Filed May '7. 1956 NEEDLE LOOM SHRINKING l 5 I INVENTOR. ZONE MANFRED T. HOFFMAN WWW United States This invention relates to the manufacture of felt, and more particularly to felt of synthetic fibers.

It is one object of the invention to provide improved methods for manufacturing felt products of heat-shrinkable or thermo-shrinkable fibers such as, for instance, polyester fibers.

It is another object of the invention to provide methods for manufacturing felt products which consist preponderantly of synthetic heat-shrinkable fibers comprising only relatively small additions of fibers of animal origin such as, for instance, sheep wool and fur of other animals.

Another object of the invention is to provide a method for manufacturing bonded felt which has improved surface qualities and more particularly little or no tendency of pilling, i.e. of formation of lumps of fibers on the surface thereof, generally referred to as pills.

Another object of the invention is to provide a process for making bonded felt of inexpensive fibers with simple and inexpensive machinery and of combining a plurality of operations which are normally effected sequentially into one single operation, or simultaneous operations, respectively.

Another object of the invention is to provide a process for manufacturing felts of synthetic fibers having increased laminar strength.

Non-woven felts may either be prepared from fibers of animal origin, or from heat-shrinking or thermo-shrinking fibers, or from mixtures of both kinds of fibers. Animal fibers have a tendency to turn, twist, bend, and entangle during so-called hardening and fulling operations performed in the presence of moisture nad heat and resulting in the conversion of a batt into a sheet of felt. In other words, the denier of such fibers does not, or does not significantly, change during the felting process. The shrinkage resulting in felt-formation occurs in the body of fibers rather than in the individual fibers. The situa tion is entirely different with regard to synthetic fibers. These fibers can be manufactured to be heat-sensitive, or heat-shrinking, or thermo-shrinking. Therefore, such fibers have felting properties, though of another nature than fibers of animal origin, and can be used for manufacturing felt products. Their felting properties are predicated upon their shrinkage under the action of heat.

Because of the inherent difference in the felting properties of fibers of animal origin, on the one hand, and synthetic heat-shrinking fibers, on the other hand, two different felting technologies have been evolved in the past for each of the two kinds of fibers. Where mixtures of synthetic fibers and of animal fibers were used in the past, the former were added to the latter in relatively small proportions, and the conversion of the batt into felt was predicated on conventional animal felt producing procedures.

I have discovered the surprising fact that certain processes which were used heretofore only in the manufacture of felt of fibers of animal origin lend themselves particularly well to the manufacture of felt of thermo-shrinking atent ice 2 fibers, and yield such felt of far superior quality than the felt of synthetic fibers known heretofore.

I have also found that improved felt products of synthetic fibers may be obtained by heating a batt which has been pre-punched in a needle-loom to the point where some tackiness of the fibers occurs and the fibers begin to shrink which, in the case of polyester fibers, might be in the order of 100 to 200 deg. C., and simultaneously subjecting the batt to a rolling and squeezing action whereby bonding of some of the fibers constituting the batt may be achieved and the batt thereby more thoroughly condensed.

It is well known in the art of felt making that the scaly surface of natural fibers tends to cause mutual mechanical interlocking of engaging fibers. I have discovered that it is possible to achieve an equivalent mechnical interlocking of thermo-shrinking fibers by appropriate heat treatment thereof up to the point where some tackiness occurs, combined with an appropriate simultaneous mechanical treatment of the batt causing bonding of some of the constituent fibers thereof.

I have further found that it is possible to convert batts comprising both fibers of animal origin and thermoshrinking fibers into very satisfactory felt products, irrespective of the ratio of both kinds of fibers, and even if the quantity of synthetic thermo-shrinking fibers in the mixture is preponderant, provided that the composite fiber batt is subjected to conditions which cause simul-.

taneous shrinking, or change in denier, of the thermoshrinking fibers, and turning, twisting, bending, entangling, entwining and interlocking of the fibers of animal origin with the thermo-shrinking fibers.

Other objects and advantages of the invention will, in part, be obvious and in part appear hereinafter.

For a more complete understanding of the invention reference may be had to the following detailed description thereof, taken in connection with the accompanying drawing, wherein:

Fig. 1 is a side elevation diagrammatically illustrating a system for producing bonded felt according to this invention;

Fig. 2 is a front view of the roller operating mechanism for the multiroller structure shown in Fig. 1;

Fig. 3 is a side elevation diagrammatically illustrating another system for producing bonded felt according to this invention;

Fig. 4 is a front view of a pair of working rollers forming part of the system shown in Fig. 3 their spacing having been increased to show the complete outline of each roller; and

Fig. 5 is a front view of a novel quilt-like felt product obtained by means of the system illustrated in Fig. 3.

Referring now to Fig. 1, reference numeral 1 has been applied to indicate the cylinder 1 of a carding machine comprising a number of workers or strippers 2 and the dofiing cylinder 3. The carding machine is being supplied with a fibrous material including heat-shrinkable fibers, preferably polyester fibers. Carding machine 1, 2, 3 forms a web of fibers which web is being carried away by the apron 4. Actually, apron 4 carries away a plurality of superimposed carded webs forming a batt, the batt-forming webs being produced by a plurality of carding machines of which but one has been shown in Fig. 1. Reference numeral 5 has been applied to indicate the batt formed by a plurality of superimposed carded webs of heat-sensitive, i.e. heat-shrinking fibers. The batt formed on apron or conveyor belt 4 is supplied to a needle loom 6 where batt 5 is being punched. The needleloom-punched batt 5 is then supplied to a multiroller machine, generally indicated by reference numeral 7. A bank of infrared rays emitting incandescent lamps 8 is arranged above the multiroller 7, and raises the temperature of the batt sufliciently high to cause shrinking of the thermo-shrinking fibers of which batt is formed, i.e. a change in denier of these fibers. While the battforming fibers are subjected to thermo-shrinking, the batt 5 is simultaneously subjected to a rolling and squeezing action, greatly increasing the shrinking action caused by heat. The temperature to which batt 5 is to be heated depends largely upon the formulation of the thermo-shrinking fibers used. With polyester fibers known in the trade as Dacron tackiness and shrinking can generally be achieved at temperatures ranging from 100 deg. C. to 200 deg. C. I prefer to subject the batt while at an elevated temperature and tacky in addition to the aforementioned rolling and squeezing action to a transverse rubbing action of sufiicient intensity to cause bonding of some of the fibers constituting said batt. While such bonding can be achieved by rolling and squeezing action alone, it can be considerably enhanced by additional transverse rubbing action. The requisite transverse rubbing action can be achieved by transversal relative movement of the rolls 9 forming the upper bed of rolls to the rolls forming the lower bed of rolls of the multiroller 7. It is also important that the needle-loompunched batt be moved in a sinuous path through the zone Where heat-shrinking is effected, this having a tendency to contribute to the entangling of the individual fibers of the batt. The sinuous path of batt 5 is achieved by appropriate arrangement of the rolls of multiroller 7 in such a way that'the two beds of rollers are out of registry. As intimated above, bonding of the fibers performed by rolling and squeezing of the fibers and enhanced by transverse rubbing is a synthetic equivalent of interlocking of scaly fibers of animal original during conventional felting operations.

The transverse rubbing action by relative transverse motion of the two beds of rolls 9, 10 is optional. Enhanced condensing and fiber-bonding may also be obtained by driving different rolls 9, 10 of the multiroller 7 at different surface speeds. As a general rule, transverse rubbing action during the heat-shrinking of fibers seems to be the better way to achieve the synthetic equivalent of mechanical interlocking of scaly fibers of animal origin.

Referring now to Fig. 2, the left portion thereof shows one of the upper rolls 9 and one of the lower rolls 10 of the multiroller 7. Reference numeral 11 has been applied to generally indicate a drive for the rolls 9. Drive 11 operates transmission wheel 12 and crank mechanism 13. The linkage 14, 15 pivoted at fixed point 16 is being driven by crank mechanism 13, so as to rock from left to right, and back to the left, etc. Linkage 14, 15 operates a linkage 17, 18 to the left end of which bearing 19 for the shaft 21 or roll 9 is secured. Bearing 19 is arranged between two collars 20 forming integral parts of shaft 21 of roller 9. Hence shaft 21 moves back and forth together with linkage 17, 18. Shaft 21 supports a worm wheel 22 meshing with a spindle 23 operated by wheel 12, thus imparting rotational movement to shaft 21. To this end worm wheel 22 is keyed to shaft 21 in such a way as to rotate jointly with shaft 21 while permitting oscillatory motions of shaft 21 in a direction longitudinally thereof relative to worm wheel 22. Each of the working rolls 9 forming the upper bed of working rolls is actuated in the way shown in Fig. 2. The actuating mechanism of the rolls 10 forming the lower bed of rolls has not been shown in Fig. 2. It may be the same as that for the upper bed of rolls 9, except that the means for imparting a transverse rocking movement to the rolls may be omitted for the lower bed of rolls 10.

. Referring now to Fig. 3, the left portion thereof shows three rolls 24, 25 and 26 of which each is formed by a wound carded web of synthetic heat-shrinkable fibers to which some other fibers, such as fibers of animal origin, may be admixed, if desired. The three webs are superimposed and moved from left to right, as by means of an apron, not shown. The batt 5' formed by superimposing three carded webs is fed into the nip of a pair of cooperating pressure rolls 28, 29 where the batt is pre-condensed. The pre-condensed batt is then fed into a needleloom 6' and punched therein. The batt 5', upon being punched in needle-loom 6, is moved farther to the right into a shrinking zone where it is heated to cause shrinking of its constituent thermo-shrinking fibers. Heating is preferably effected by supplying the rolls 9' and 10 of multiroller 7 with steam yet, as an alternative, batt 6 may also be heated by means of a bank of infrared rays emitting incandescent lamps 8. Reference numeral 30 has been applied to indicate a system of spray nozzles producing fine sprays of hot water at a plurality of points spaced longitudinally of needle-loom-punched batt 5'. The moist treatment is indicated where web 5' is made up in part of fibers of animal origin, in addition to a preponderance of synthetic heat-shrinkable fibers. The number of rolls of multiroller 7' may be increased to suit the specific requirements of each invidiual case and may be much larger than shown in Figs. 1 and 3.

In a specific embodiment of my invention I cause selectively increased condensing of batt 5' at spaced points thereof by subjecting the batt while heated and in tacky, or in semi-tacky condition, to a simultaneous rolling and squeezing action at spaced points thereof. Considering Fig. 3, the rollers 10 of the lower bed may all have a smooth cylindrical surface, but some of the rollers 9' of the upper bed may have a pattern of ridges projecting radially outwardly and causing local increased bonding and condensing of batt 5. Fig. 4 shows a lower roll 10 having a smooth surface and an upper roll 9' whose surface is covered with a system of square ridges or projections tending to cause selective increased condensing or increased spot-bonding of tacky fibers.

Fig. 5 indicates the quilt-like appearance of a bonded felt obtained by this process. This quilted felt has very unusual properties. It may be used to produce a variety of pad-like articles, packing materials and insulating materials. The geometric pattern produced by increased local condensing and spot-bonding of the fibers imparts to the material a degree of dimensional stability not encountered heretofore in any soft felt-like product. The areas where there is relatively less condensing and spotwelding of fibers impart to the material an unusual quality of softness and fiufiiness, greatly increasing its protective value and its thermal insulation properties.

It will be apparent from the foregoing that the process illustrated in Figs'l or 3 when practiced with uneven rolls of the type illustrated in Fig. 4 enables to produce a number of products which vary widely, and whose stiffness varies not only with quantitative changes in the treatment thereof but also with changes of the fibrous constituents of the original batt.

The process may yield a product which has quilt-like properties in as much as its relatively undercondensed areas result in quilt-like softness, whereas its relatively overcondensed areas result in a very high degree of laminar strength. If desired the roll with the pattern of ridges thereon may be oscillated to produce a more gradual change between the areas where the batt is highly condensed and the areas of the batt where the batt is not highly condensed.

It will be understood that I have illustrated and described herein preferred embodiments of my invention only and that various alterations may be made in the details thereof Without departing from the spirit and sinuous path through a shrinking zone and subjecting said batt while in transit through said zone to a sufficiently high temperature to cause shrinking and tackiness of said heat-shrinkable polyester fibers, and of subjecting said batt while undergoing heat-shrinking to simultaneous rolling and squeezing action and to transverse rubbing action of sufficient intensity to cause bonding of some of said polyester fibers.

2. The process of making bonded felt from synthetic fibers comprising the steps of supplying a batt including thermoplastic heat-shrinkable fibers to a needle-loom, of punching said batt while in transit through said needleloom, of advancing said needle-loom-punched batt in a sinuous path through a shrinking zone and of shrinking said batt therein by the application of heat, of subjecting all of said batt to simultaneous rolling and squeezing action and transverse rubbing action, and of causing selectively increased bonding of said batt at spaced points thereof by subjecting said batt at said spaced points thereof to an increased simultaneous rolling and squeezing action and transverse rubbing action.

References Cited in the file of this patent UNITED STATES PATENTS 1,589,626 Chudoba June 22, 1926 2,437,689 Francis Mar. 16, 1948 2,464,301 Francis Mar. 15, 1949 2,502,361 Zeigler Mar. 28, 1950 2,636,248 Lee Apr. 28, 1953 2,723,935 Rodman Nov. 15, 1955 FOREIGN PATENTS 458,802 Great Britain Dec. 28, 1936 

1. THE PROCESS OF MAKING BONDED FELT FROM SYNTHETIC FIBERS WHICH FELT IS SUBSTANTIALLY FREE FROM THE TENDENCY OF PILLING, SAID PROCESS COMPRISING THE STEPS OF FORMING A BATT OF SHRINKABLE FIBERS ONLY INCLUDING HEAT-SHINKABLE POLYESTER FIBERS, OF SUPPLYING SAID BATT TO A NEEDLE-LOOM, OF PUNCHING SAID BATT WHILE IN TRANSIT THROUGH SAID NEEDLELOOM, OF ADVANCING SAID NEEDLE-LOOM PUNCHED BATT IN A SINUOUS PATH THROUGH A SHINKING ZONE AND SUBJECTING SAID BATT WHILE IN TRANSIT THROUGH SAID ZONE TO A SUFFICIENTLY HIGH TEMPERATURE TO CAUSE SHINKING AND TACKINESS OF SAID HEAT-SHINKABLE POLYESTER FIBERS, AND OF SUBJECTING SAID BATT WHILE UNDERGOING HEAT-SHRINKING TO SIMULTANEOUS ROLLING AND SQUEEZING ACTION AND TO TRANSVERSE RUBBING ACTION OF SUFFICIENT INTENSITY TO CAUSE BONDING OF SOME OF SAID POLYESTER FIBERS. 